Let's be totally honest here. We've all made mistakes in our day to day life and our workplace is no different so whether it is down to human error or technical errors, mistakes are made, but it's what we actually do about it that is more important than the actual mistake itself.
There are many reasons why we may have made a mistake at work. Tiredness, stress, an excessive workload, not fully understanding what is expected and even at times, inadequate training can all play a part. However, once you realise you have made a mistake, it is imperative that you rectify it yourself immediately if possible then to inform your manager of the action you have taken. An example of this would be if you were responsible for contacting certain key companies regarding information they required but somehow you omitted three companies off your email list, then realised they were missing and duly contacted them with the information and an apology for the delay for responding. In a scenario similar to this then all should still be well.
Yet, there may be an occasion where a serious mistake is made. In this case, your manager must be informed as soon as possible and you should offer a full and truthful explanation regarding what has happened whilst at the same time offering a sincere apology and not an excuse. Offer to work to find a solution and to right the wrong. This will show your manager how resourceful and dedicated you are in times of pressure.
It is important to remember that we are human and we can all make a mistake regardless of our role in a company, even our manager will have made the odd mistake.
Never become tempted to try and cover up any mistake or to deny it as ultimately you could be jeopardising your job as well as letting yourself, your colleagues and your company down. It is far better to own up and to feel that slight initial embarrassment than to end up having to explain to your manager why you took the decision to ignore a mistake.
If we can recognise our own oversights and not to direct the blame on to other colleagues, if our intentions are honourable and we are genuinely accepting of our error and have done all we can to correct our mistake, then our manager will be more than likely impressed with the integrity, honesty and quick thinking that we have displayed.